The present invention relates to an inductive plasma applicator, a vacuum vessel comprising this inductive plasma applicator, and a surface treatment device comprising the vacuum vessel.
Plasma treatments are widely used in the industry for many purposes, such as surface activation, in particular for polymer-based materials, material thin film deposition, layer etching, etc. Many applications also require that the plasma treatments are performed on large area substrates, ranging from about one square-centimeter to several square meters. For example, architectural glazings implement thin film stacks that are deposited on glass panels of about 20 square-meters. Thin film stacks are also deposited on continuous polymer-based sheets in roll-coaters.
According to a well-known implementation mode of plasma treatments, the plasma is energized with a RF frequency magnetic field. The magnetic field is produced in a plasma volume using a coil which is supplied with an AC current. The AC magnetic field produces in turn an electric field which transfers energy to the plasma.
Actually, a processing time for such plasma treatment depends on physical parameters of the plasma which is implemented. For example, the magnetic field in the plasma volume is an important parameter, as well as the separating distance between the surface to be treated and the location where the plasma density is the highest. So, a plasma treatment device should be designed taking into account values for such parameters which are optimized for the treatment and the application of concern. Therefore, there is a need for supplying plasma treatment devices with design and geometry parameters which can be varied easily on order.
Another need relates to large area plasma sources, which are suitable for performing uniform treatments of wide substrates. In particular, such large area plasma sources should be suitable for implementation in vacuum devices  with fixed or moving substrates.
A further need is to provide plasma generating devices which are suitable for being installed easily in many vacuum vessels, with short installation time.
A further need is also to provide plasma generating devices with unit cost which is reduced with respect to the plasma sources currently available.
Therefore, an object of the present invention is to provide a plasma source which meets at least one of these requirements.